Air brake



Feb. 9, 1937. c. A. CAMPBELL AIR BRAKE Filed May 29, 1936 Ennentor@ha/ziw fhCh/m abdlb Gttornegs Patented Feb. 9, 1937 I v UNITED STATESPATENT OFFICE AIR BRAKE Charles A. Campbell, Watertown, N. Y., assignorto The New York Air Brake Company, a corporation of New JerseyApplication May 29, 1936, Serial No. 82,613

4 Claims. (01. 303-1) This invention relates to air brakes, and parwhichpass through wings 35 and 36 on valves ticularly flow controlling chokesand means for 21 and 29 respectively. Pins 34 are shouldered at keepingsuch chokes clean, 3! and 38, the shoulders being so spaced that Whilegenerally useful in any case where a piston l9 first moves a shortdistance idly, then metering choke is used in conjunction with abyengages and unseats valve 29 and on further uppass or other flow portso arranged as to supply ward movement facilitated by the opening of acleaning air jet, the invention was developed Valve 29 unseats valve 27.for use in vent valves or quick action valves and The mechanism so fardescribed conforms genwill be described as used in a vent valve of theerally to the disclosure of the prior patent above type disclosed in thepatent to Campbell No. identified. Important features of novelty will 11,938,738, issued December 12, 1933. now be pointed out.

In the drawing,- Piston I9 is conical in section and in its upper Fig. 1is a vertical axial section through such face is divided by three radialwebs 39 into three a vent valve with the invention incorporated. pockets4! out of the path of air currents and Fig. 2 is a fragmentary viewshowing a porhence adapted to collect any dust or scale that 15 tion ofFig. 1 with the metering choke in axial may be present. section. Belowring 2| the periphery of piston I9 is Fig. 3 is a plan view of thepiston partly broken out back to form a segmental clearance 42 (see awayto show the bypass which directs the cleanparticularly ig. 3) and fromthis clearance leads ing jet against the choke. a generally radialbreather port 43. Air dis- 20 In the drawing, the body of the vent valvecharging in a radially inward direction from this comprises a housing 6with brake pipe connecport impinges upon the upper projecting conicaltion 1 having bolting flange 8 and screen 9. A end of choke plug 44.Plug 44 has an axial bore removable cap II closes an opening in the top45 and near its upper end four radial passages of housing 6. Bolted tohousing 6 is a cup-like 45 each preferably of the same diameter as theshell l2 enclosing the balancing chamber I3 radial bore, so that theaxial bore, below said (sometimes called a quick action chamber). radialports, performs the metering function.

Clamped between body 6 and shell I2 and Operation sealed by gasket IIIis cylinder bushing M with sealing rim l5 and pendant yoke I6, whichlast In charg ng the system at normal rates of brake 30 carries hub II.Hub I! serves as a guide for pipe rise, the parts assume the positionshown stem I8 of emergency piston IS, the piston workn g. a d Chargingow to hamber I3 is ing in bushing I4 and having a metallic packt ou ypss 43 and Choke P 44 in paralleling ring (snap ring) 2|. Piston l9 alsocar- If brake pipe pressure rises more rapidly, say ries a rubber orlike gasket 22 which seals on at the rate encountered in the leadingtwenty 35 rim IS in the lowermost position of the piston. cars or so,piston I9 overpowers spring 25 and A cup 23 threaded on hub I'I guides ashiftable gasket 22 seals on rim l4 so that charging flow stop 24 urgedupward by spring 25 so that it to chamber I3 is limited to the capacityof choke normally engages the lower face of hub IT. The n plus 44. hisprotects inst v rc ar e parts are so dimensioned that in the uppermostand when the pressure difierential on piston I9 40 position of the stop24, the stop engages stem diminishes sufficiently piston I9 will resumethe IB and holds piston I9 in such position that gasposition of Fig. 1.

ket 22 clears rim l5, but the piston may be During reductions of r k p pp ur at forced down against the resistance of spring 25 service ratespiston l9 may rise idly until shouluntil the gasket seals on the rim.ders 38 engage wings 36. Port 43 and choke in 45 In housing 6 is anupstanding annular valve p u 44 then permit back w from C ambe 3 -seat26 on which seats the main vent valve 21. to the brake pipe at such ratethat pressure in Valve 2! has a central port surrounded by seat chamberl3 falls at a service rate.

28 on which seals the pilot vent valve 29. A coil Since the air jetdischarging through port 43 compression spring 3| seated within cup 32carimpinges d e t y o the projecting pper end 50 ried by cap II reactsdownward on valve 29 and of choke plug 44, the upper end of the plug andhence tends to seat both valves. Anatmospheric consequently the radialpassages 46 are swept port, indicated in dotted lines as 33, leads fromfree of dust and scale, and any other foreign the space within seat 26.matter which would tend to clog the choke. The

5 Piston l9 carries three upstanding pins 34 pockets 4| tend to collectany dust so dislodged.

The cleaning action above described occurs on every service reductionand even more actively on emergency reductions.

In emergency reductionsthe brake pipe is suddenly vented, so that thepiston l9 moves up full stroke unseating' valves 29 and 21 to completethe venting. The effective pressure causing flow through port 43 is thenat its maximum value, so'that flow is rapid and the scouring action ispronounced.

As stated, the inventionis capable of embodiment in specificallydifferent brake valves in which a metering choke and a bypass or otherport are capable of arrangement to efiect the cleaning function. V

What is claimed is, r

1. In a fluid pressure brake system, the combination of means forming aflow controlling choke,'and a bypass therearound distinct therefrom; andpressure responsive means for opening and closing the bypass, the partsbeing so arranged that the choke controls the rate of flow when thebypass is closed, and'fiow through the bypass exercises a cleaningaction on the choke When'the :bypass is open. r

' 2. In a fluid pressure brake system, 'the combination of means forminga chamber subject to brake pipe pressure; a reservoir; a shiftable 1 inga bypass also between said chamber and reservoir; and means operablebymotion of said piston for opening and closing said bypassfthe bypassbeing arranged to direct air discharging therefrom against a portion ofsaid choke fitting to clean the same.

3. In a fluid pressure brake system, the combination of means forming achamber subject to brake pipe pressure; a reservoir; a shiftable pistoninterposed between said chamber and reservoir; a choke fitting mountedin said piston for limiting flow from said chamber'to said reservoir,said fitting having a projecting entrance end on the chamber side' ofsaid piston; and means forming a bypass through said piston around saidchoke, said bypass being opened and closed by the shifting of saidpiston and being arranged to direct air flowing from the reservoir 1through the bypass against the projecting end of said choke fitting. V

4. In a fluid pressure'brake, the combination of means forming a chambersubject to brake pipe said' reservoir," said fitting having a projectingentrance end within and above the bottom of such pocket; and meansforming a bypass through said piston said bypass being opened and closedby shifting of the pistonand being arranged when open to direct airflowing from the reservoir substantially horizontally against theprojecting end of said choke fitting, toclean the same.

V CHARLES A. CAMPBELL.

